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John Popelish John Popelish is offline
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Default critique SMT pcb ? (PCB rev 1)

robb wrote:

Also i do not know how one would fix the capacitive load to
preven oscillation ? The only solution i recall for these
oscillation prolems is adding a capacitor ? hopefully my addition
of small cap across opamp will solve both problems ?


If it was my board, I would add provision for a resistor
between the opamp output and the pair of capacitors so that
I could try adding a 10 to 47 ohm resistor. If it works
without any, you just jump that component.

Then run the ground buss directly from the capacitors, not
from the opamp output. It won't be a stiff, but then, the
battery is not a stiff voltage source, either.

Unfortunately, this is not the only circuit weakness, but
you seem intent on getting something built, rather than
refining the circuit, first. For instance, I think it is
might be quite practical to eliminate the ground bus half
way between +4.5 and -4.5 volts rails, all together. Most
of the circuit is only using the +4.5 to ground part of the
battery voltage, and the ground reference generator has to
waste the other half by absorbing their currents.
The capacitors connected directly to an opamp output is the
first clue that the designer has not finished thinking the
circuit through.

--
Regards,

John Popelish